Ribbed basic refractor roof



June 25, 1963 R. P. HEUER RIBBED BASIC REFRAc-TORY RooF 2 Sheets-Sheet 1Filed May 24, 1960 V Lug 2 Sheets-Sheet 2 R. P. HEUER ZNvEN-roa /mfae/Heder ATTORNEYS RIBBED BASIC REFRACTORY ROOF June 25, 1963 Filei May 24,1960 United Stats Patent 3,094,952 RIBBED BASIC REFRACTORY ROGF RussellPearce Heuer, Villanova, Pa., assignor to General Refractories Company,a corporation of Pennsylvania Filed May 24, 1960, Ser. No. 31,384 4Claims. (Cl. 110-99) The subject matter herein disclosed forms acontinuation-in-part of the matter set forth in my rco-pendingapplicat-ion Serial No. 577,3lvl, tiled April 10, 1956, now abandoned,and the invention relates to a refractory roof comprising rib brick,intervening brick, .and supplemental refractory brick superimposedl onthe intervening brick and the ribs.

An object of this invention is to obtain improved resistance to spallingin supplemental refractory brick in a ribbed basic furnace roof, thesupplemental refractory brick suitably being installed while the furnaceis oper-ating, for the supplemental brick thereafter to endure beyondthe expected life `of the intervening brick in the roof and toco-function with the rib brick in the roof.

A further object is the provision of internal oxidizable 'ferrous platemeans in the basic refractory roof brick, which plate means divides therefractory of the individual supplemental brick into a plurality ofintegral partitioned zones or sections -which are in series with eachother and with the brick in the adjacent ribs, thus for the supplementalbrick to resist spalling and more reliably remain in place -while beingsupported by the ribs of the roof.

A further object is that 'of providing a plurality of brick in theindividual ribs, laterally of the ribs, and to` have these brick inser-ies with the refractory sections of the supplemental brick which areadapted to span the ribs while being supported by the ribs.

A still further object is the provision of external oxidizable ferrousplate means on one or more lateral outside `faces of the supplementalrefractory roof brick t through co-molding this plate means with therefractory of the supplemental brick, and preferably introducing theinternal plate means integral with the external plate means.

Other objects of the 4invention in part ywill be obvious and in partpointed out more fully hereinafter.

In the drawings I have chosen to -illustrate a few only of the numerousembodiments in which my invention may appear, selecting the forms shownfrom the standpoints of convenience in illustration, satisfactory operattion and clear demonstration of the principles involved.

FIGURE l is a fragmentary diagrammatic transverse `section of an openhearth steel furnace of the general character employing the roof of theinvention.

FIGURE 2 is a fragmentary enlarged section on the FIGURE 3 is a lateralelevation of the supplemental refractory brick of the invention, lookingat the small lateral side.

FIGURE 4 is a lateral elevation of the brick of FIG- URE 3, looking atthe large lateral side.

FIGURE 5 is an enlarged perspective of one of the supplemental basicrefractory roof brick of the invention showing one arrangement ofexternal and internal oxidizable ferrous metallic plate means.

FIGURE v6 is a perspective view similar to FIGURE 5, Showing anIalternative arrangement of the plate means.

FIGURE 7 is a `diagrammatic transverse vertical section showing themolding of the brick of the invention.

FIGURE 8 is a fragmentary section corresponding to i FIGURE 2, butdiffering in the respect that the supplemental brick employed betweenthe roof ribs are of the form represented in FIGURE 6.

FIGURES l and 2 illustra-te a furnace, suitably an "ice open hearthsteel furnace, comprising |a hearth, not shown, framework 20 and frontwall 21 and :back wall 22 supported by the side framework, skewbacks 23and 24 at the top of the front wall and back wall supported by 4thewalls and by the framework, and a roof 25 supported partially by theskewbacks and partially by suspension 'from overhead framework .26.

The roof consists of rows of relatively elongated or ribbed refractorybrick 27 suitably arranged in pairs as shown in FIGURE 2, Iand extending-arcwise of the furnace to produce the ribs. Each of the ribbed brickhas a hot end 28, a cold end 29, a straight lateral side 30 in the planeof the arch, a lateral side 31 and also radial sides 34. Lateral side 31includes a straight portion 32 in the plane of the arch and a wedge orltapered portion 33 at Ithe upper end. The rib brick are preferablybasic, consisting of magnesia, chrome, chrome-magnesia ormagnesia-chrome.

Interposed between the Velongated or ribbed brick at the hot end `areintervening rows 35 of relatively short refractory brick, which may beof wedge or key construction as desired, and have hot ends 36, flatarchwise surfaces 37, radial surfaces 38 and cold ends 40. Theintervening brick are preferably basic, consisting of magnesia, chrome,chrome-magnesia or magnesia-chronie.

The relatively elongated brick 27 are Edesirably independently supportedfrom overhead structure in any desired manner in the form shown. Arcuatemetallic beams 41 carried by suspension elements 42 from the overheadstructure 26 conform to the cold ends of the ribbed brick. Holes 43.across the ribbed brick near the cold ends receive metallic hangers 44which are suitably bands of wire extending around the beams 41- andtwisted at 45.

The intervening relatively short brick 35 are desrably sprung fromtheskewbacks 23, 24 at -the front and back of the furnace.

The use of dot and dash lines in .FIGURE` 2 suggests destruction at thehot ends of the brick to form a Vhot end line 46 after the brick havebeen .in service for some time. Y

One of the advantages of .the structure of FIGURES 1 and 2 is that theintervening brick 35 can be backed up by supplemental brick `47 at thecold end after the roof is partially consumed, as shown Iin FIGURE 2.These supplemental brick greatly increase the life of the roof.

It is customary practice in operating such a roof to allow the roof toburn away as shown in FIGURE 2 to` some level 46 at which it becomesnecessary to place supplemental brick which will be held in position bythe ribbed brick. This operation lof placing the supplemental brick canbe performed while the furnace is operating at high temperature.

As the roof continues to wear away the intervening brick 35 below thesupplemental brick are completely eliminated and the supplemental brickare exposed to the flame of .the furnace. Due to the character of theconstruction, the exposed hot faces of the supplemental brick are large,being perhaps twelve inches long by two and one-half inches wide. I havefound that these brick having such a large Working face tend to spall=very rapidly. :It is not possible to make the exposed faces of thesebrick smaller because they have to be long enough to reach betweenthe'successive rib brick of the roof. l

I have discovered, however, that the spallng above referred to isgreatly reduced if the supplemental brickV are molded of a basicrefractory composition consisting of magnesia, or mixtures of magnesiawith alumina and/ or chromite, and where the amount of -magnesia presentis 10 percent or more by weight of the refractory composition. Then bycomolding this composition with internal oxidizable ferrous metal platemeans which extends between the hot face and'coldface of thesupplemental brick and subdivides the refractory into a plurality ofpartitioned sections or zones integrallytinseries with each other andthe plate means, the partitioned brick behaves as if a number of smallbrick were present, thus greatly increasing the resistance to spalling;At the same time the brick functions as a large brick from thestandpoint of support between the ribs and therefore the variouspartitioned sections introduce no problem in the sense of needingadditional support in the roof. The internal oxidizable ferrous platemeans also contributes a strengthening function inthe brick` throughbeing in intimate contact with the magnesia in the refractorycomposition and through effects which the operating conditions of thefurnace have upon the plate means andthe refractory when thesupplemental brick are exposed to the flame of the furnace.Strengthening zones of magnesioferrite develop in the brick by virtue ofthe ferrous substance of the plate means and the adjacent magnesia inthe brick being altered to magnesioferrite which theny stands as abarrier against spalling and cracking at the hot face of thesupplemental brick. The overall pattern of spalling and cracking whichone might normally expect is very appreciably altered bythe internalplate means `and by the magnesioferrite barriers which ultimately occurin the brick as the result of its use in the furnace. The supplementalbrick accordingly are well equipped to share long life in the roof withthe rib brick which still remain to afford support and to contributetheir refractoriness in the roof. Usually, the rib brick, theintervening brick, and the supplemental brick all are made havingsubstantially the same basic refractory composition for the sake ofuniformity although in certain instances these basic refractorycompositions may differ dependingfor example upon specific needs.

It is also very desirable to provide lateral surface plates ofoxidizable ferrous metal on the supplemental brick.

The method of molding is illustrated by FIGURE 7 which shows a moldingpress 48 comprising relatively movable upper and lower dies 50 and 51and mold sides 52 forming a moldcavity 53- which is desirably of wedgeor taperedcontour in plan view.

Before filling the rnold with refractory, a lateral surface plate 54 isdeirably placed :on the'bottomdie, and preferably secured to the surfaceplate and extending upwardly ina generally longitudinal direction areinter-nal plates 55, also tabs` 56 lanced out from the surface plateextend upwardly to engage in the refractory. The lancing of the tabsleaves openings 57 in the surface plate, as best seen in FIGURE 5.

The mold is filled with a loose refractory mass 58 as later explained.On the bottom of the top die 50 is placed a cooperative and suitablyidentical surface plate 54 having secured thereon downwardly protrudinginternal plates 55 and downwardly protruding tabs 516. The internalplates 55 from theA top plate combination desirably are aligned with thesimilar internal plates from the bottom plate combination. The upperplate combination is suitably held on the upper die by a magnetic chuck,a me,- chanical gripper or by an adhesive, as desired, during themolding.

When the upper and lower dies move relatively together, the internalplates are buried in the refractory brick by comolding and the tabs aresimilarly buried while the surface plates are united to the brick by co-Imolding through the internal plates and the tabs.

In the final brick `as shown in FIGURE 5, the internal plates aresuitably slightly diverging vbut generally transverse to the hot face 58of the brick. The internal plates are close togetherbut preferably donot meet at 60 near the cent-er. The internal plates desirably extendsubstantially Ythe entire distance from the hot face 58 to the coldface61, although considerable advantage will be obtained from theinvention if, beginning lat about the hot face of the brick, they extendmore than 75 percent of the distance to the cold face and excellentresults can be obtained if the internal plates extend percent lof thissame distance.

In the form shown, the Iarcwise faces 62 of the brick are slightlywedge-shaped to conform to the arch and carry the external plates 54.The radial side surfaces 63- are pronouncedly wedge-shaped and engageagainst the wedgeV surfaces 33 to support the supplementalr brick fromthe rib brick. The internal plates divide the refractory of the brickinto four partitioned sections which are in series laterally of the ribsof the roof (see FIGURE 2) and the sections also are in series with theribbrick widthwise of the adjacent ribs. By having a plurality of ribbrick widthwise of the ribs these individual brick have an influence onthe pattern of cracking and spalling ofthe roofv and the inuence isshared with the partitioned sections of the supplemental brick.

The metal used for the external and internal plates is preferably steelor iron, including plain carbon steel, alloy steel or stainless steel.The plates are all sheet material, preferably having a thickness ofapproximately between 1/32 inch and 1A inch, depending upon theinstallation.

In the preferred embodiment as shown, the surface plate 54 is desirablyconnected as lby welding to the internal plate or plates 55 which extendtransversely from the surface plate preferably in line with the internalplate extending from the opposite side. Thus the internal plates, in theinstalled positions of the supplemental brick, are disposed generallyarcwise of the roof and are between the corresponding pair of adjacentribs of the roof. The partitioned sections in the supplemental brick maysuitably lie in arcwise rows extending from the front to the back of thefurnace and which occupy positions between the ribs 'and advantageouslyyoccur with plural arcwise rows of the rib brick in each of theindividualfribs and so that the hot face of the roof is continuouslyformed having small areas of basic refractory which at least to someextent are -isolated one from the other against carry-over of crackingand spalling.

The surface plates may if desired be of U-shaped formation to provideexternal plates at -the radial sides. In

order to 4accomplish the molding With a U-shaped plate,

or several ina particular brick, will depend upon the overall length ofthe supplemental br-ick or the distance between ribs. In the simplestform it is sufficient to use only one internal plate which may dividethe brick -into l In other cases two, three, 1 or even four or moreinternal plates preferably spaced at l equal distances from each otherand from the radial side two approximately equal parts.

of the brick will provide suitable arrangements.

The internal plates should be `at right yangles to the 3 external platein order to lie in the direction of the motion t of the pressing die.The pla-ne of the internal plates may also if desired be perpendicularto the internal surface of the roof -although slight inclination isproper, as shown in FIGURE 5, so that the internal plate nearest theradial side of the brick is almost parallel with the radial side.

The internal plates oxidize 4in service and the iron oxide formed by theoxidation of the internal plates reacts with the magnesia in the basicrefractory to form magnesioferrite which partly diffuses into therefractory and causes no appreciable volume expansion.

Thus the oxidizable internal plates partition the brick into two or moreparts, each of which behaves as if it were la sm-all individual brick.On the other hand, the supplemental brick is supported `as `a unit, butthe spalling behavior is that characteristic of the `small component`parts.

The oxidizable iron or steel plates exert a pronounced tendencyl toprevent spalling off of the hot ends of the brick. The m'agnesioferritewhich forms in the vicinity of the plates near the hot ends is highlyrefractory and tends to create a strengthening plane running transverseto the span of the Ibrick between the adjacent ribs.

The planar distribution breaks up the forces which cause cracking la-ndthus tends to prevent crack propagation -across the brick from one sideof the magnesioferrite to the other. Thus spalling otf at the hot end isprevented or retarded. The tapered ends of the supplemental brick whichrest upon the suspended ribs are less prone to severe cracking andspalling since the carry-over of severe cracks is arrested by themagnesioferrite.

Any suitable basic refractory containing magnesia as above `describedcapable of use without k-iln firing may be employed. A low temperaturebinder will desirably ybe used such as sulfuric acid or an organicbinder. After molding the brick are cured and/ or dried and are thenready for use. The external plates on the brick where used tend toprotect the brick against damage during shipment. The supplemental roofbrick are usually installed in the unred condition and are tired throughfurnace operation, at which time the magnesioferrite is formed.

While the illustration in FIGURE 1 shows an arc structure, it will beunderstood that the roof may be flat if desired,

While I have shown the internal plates attached to the external plates,it will be understood that the internal plates may be separate and maybe used even without external plates.

FIGURE 6 shows a supplemental brick having internal plates 55 providedwith tabs 56 on both surfaces united by comolding to the brick. Thereare also external plates 54' optionally used and having internal tabsengaging in the refr-actory land held by comolding.

In this case the internal plates lie in a plane `generally parallel tothe pressing dies. In manufacturing these brick the bottom plate 54 isrst inserted with its tabs sticking up. Then a layer of loose refractorywhich forms the refractory portion 64 is inserted, after which aninternal plate 55 is put in having tabs extending upwardly and tabsextending downwardly. Then the loose refractory forming the brickportion 65 is inserted and another internal plate 55 follows. Then theloose refractory forming the brick portion 66 is inserted and finallythe external plate 54' is placed on the top die. In this form theinternal plates are shown extending to the radi-al edges, but it will beevident that they can extend only partially to such edges if desired.The comolding and the tabs unite the refractory and the plates togetherinto a unitary structure. The resulting supplemental brick 54 in thisinstance individually have a plurality of partitioned sections which arein series with each other and the oxidizable ferrous plates with thepartitioned sections or zones of the basic refractory, of the typehereinbefore referred to containing -at least about 10 percent magnesia,are in series which extends larcwise of the roof when brick 54 aresubstituted for the supplemental brick 54 in the manner indicated inFIGURE 8. Further, in this particular use, each partitioned section inthe supplemental brick occurs in series with the rib brick in theadjacent ribs, transversely of the ribs. Cracking and spalling again areeffectively arrested in the hot face pattern of the roof `which includesthe refractory sections of the supplemental brick 54' and the hot facesof the rib brick. The magnesioferrite which forms `from the oxidizableinternal ferrous plates 55 and the magnesia present adjacent to thesepl-ates not only produces crack 'barriers but strengthening zones sothat the supplemental brick serve quite well as the short beams whichthey are, spanning the gap between the adjacent roof ribs on which thesupplemental brick rest. In being formed, the magnesioferrite bringsabout no appreciable increase in volume and thus stresses in the roofare minimized.

In view of my 4invention and disclosure, variations and modifications tomeet individual whim or particular need will doubtless become evident toothers skilled in the art, to obtain all or part of the benefits of myinvention without copying the product shown, and I, therefore, claim allsuch insofar as they fall within the reasonable spirit and scope of -myclaims.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. A furnace -roof for use on a metallurgical furnace, comprisingskewbacks on opposite sides of the roof, metallic supporting structurerunning across the roof from one skewback to -another above the level ofthe roof, a plurality of spaced rows of basic refractory longer brickextending as ribs between the skewbacks, each of said basic refractorylonger brick lhaving cold ends and hot ends, Ibeing laterally taperedadjacent the cold ends and Khaving lateral parallel side portionsadjacent the hot ends, each of said basic refractory longer brickextending generally vertically from the hot surface of the roof throughthe thickness of the roof to the vcold end, metallic hanger supportmeans interconnecting said longer brick at the cold ends with saidsupporting structure, said longer brick being supported by said hangersupport means, intervenin-g basic refractory brick positioned betweensaid longer rib brick having a shorter length than the rib brick andextending upward from the hot surface of the roof along the lateralparallel portions of the rib brick, said intervening basic refractorybrick having lateral parallel sides adjoining the lateral parallel sideportions of said rib longer brick and said intervening basic refractorybrick 'being in plural arch rows between the adjacent ribs and supportedIby said skewbacks, independently of said rib brick, and supplementalbasic refractory brick containing magnesia in amounts of 10 percent ormore in the refractory composition thereof and being superimposed asshort beams between said longer rib brick above said intervening brickand extending laterally across said plural arch rows of said interveningbrick, said supplemental basic refractory brick having oxidizableferrous metal plates internally thereof dividing the magnesia-containingrefractory composition thereof into a plurality of partitioned sectionseach extending at least a major portion of the distance between thecorresponding hot faces and cold faces of said supplemental brick andextending in the direction toward and away from the skewbacks, each ofsaid supplemental brick having lateral tapering sides which engage thelaterally tapering sides of said rib brick and being supported by saidrib brick and thus placin-g said partitioned sections in serieslaterally with rib brick in the adjacent ribs.

2. A furnace roof of clairn 1, in which said supplemental brick haveexternal oxidizable ymetallic plates on radial faces thereof, extendingfrom one lateral tapering side to the other.

3. A furnace roof of claim' 1, in which said partitioned sections inindividual ones of said supplemental brick are in series with each otherlaterally of the adjacent ribs.

4. A furnace roof of claim l, in which said partitioned sections inindividual ones of said supplemental brick are in series with each otherarcwise of the roof.

References Cited in the file of this patent UNITED STATES PATENTS2,652,793 Heuer et al Sept. 22, 1953 2,824,529 Ries Feb. 25, 19582,903,254 Heuer Sept. 8, 1959 OTHER REFERENCES Heuer, R. P. and Fay, M.A.: The All-Basic Open Hearth European and American, Journal of Metals,pages 824-829, .Tune 1950.

1. A FURNACE ROOF FOR USE ON A METALLURGICAL FURNACE, COMPRISINGSKEWBACKS ON OPPOSITE SIDES OF THE ROOF, METALLIC SUPPORTING STRUCTURERUNNING ACROSS THE ROOF FROM ONE SKEWBACK TO ANOTHER ABOVE THE LEVEL OFTHE ROOF, A PLURALITY OF SPACED ROWS OF BASIC REFRACTORY LONGER BRICKEXTENDING AS RIBS BETWEEN THE SKEWBACKS, EACH OF SAID BASIC REFRACTORYLONGER BRICK HAVING COLD ENDS AND HOT ENDS, BEING LATERALLY TAPEREDADJACENT THE COLD ENDS AND HAVING LATERAL PARALLEL SIDE PORTIONSADJACENT THE HOT ENDS, EACH OF SAID BASIC REFRACTORY LONGER BRICKEXTENDING GENERALLY VERTICALLY FROM THE HOT SURFACE OF THE ROOF THROUGHTHE THICKNESS OF THE ROOF TO THE COLD END, METALLIC HANGER SUPPORT MEANSINTERCONNECTING SAID LONGER BRICK AT THE COLD ENDS WITH SAID SUPPORTINGSTRUCTURE, SAID LONGER BRICK BEING SUPPORTED BY SAID HANGER SUPPORTMEANS, INTERVENING BASIC REFRACTORY BRICK POSITIONED BETWEEN SAID LONGERRIB BRICK HAVING A SHORTER LENGTH THAN THE RIB BRICK AND EXTENDINGUPWARD FROM THE HOT SURFACE OF THE ROOF ALONG THE LATERAL PARALLELPORTIONS OF THE RIB BRICK, SAID INTERVENING BASIC REFRACTORY BRICKHAVING LATERAL PARALLEL SIDES ADJOINING THE LATERAL PARALLEL SIDEPORTIONS OF SAID RIB LONGER BRICK AND SAID INTERVENING BASIC REFRACTORYBRICK BEING IN PLURAL ARCH ROWS BETWEEN THE ADJACENT RIBS AND SUPPORTEDBY SAID SKEWBACKS, INDEPENDENTLY OF SAID RIB BRICK, AND SUPPLEMENTALBASIC REFRACTORY BRICK CONTAINING MAGNESIA IN AMOUNTS OF 10 PERCENT ORMORE IN THE REFRACTORY COMPOSITION THEREOF AND BEING SUPERIMPOSED ASSHORT BEAMS BETWEEN SAID LONGER RIB BRICK ABOVE SAID INTERVENING BRICKAND EXTENDING LATERALLY ACROSS SAID PLURAL ARCH ROWS OF SAID INTERVENINGBRICK, SAID SUPPLEMENTAL BASIC REFRACTORY BRICK HAVING OXIDIZABLEFERROUS METAL PLATES INTERNALLY THEREOF DIVIDING THE MAGNESIA-CONTAININGREFRACTORY COMPOSITION THEREOF INTO A PLURALITY OF PARTITIONED SECTIONSEACH EXTENDING AT LEAST A MAJOR PORTION OF THE DISTANCE BETWEEN THECORRESPONDING HOT FACES AND COLD FACES OF SAID SUPPLEMENTAL BRICK ANDEXTENDING IN THE DIRECTION TOWARD AND AWAY FROM THE SKEWBACKS, EACH OFSAID SUPPLEMENTAL BRICK HAVING LATERAL TAPERING SIDES WHICH ENGAGE THELATERALLY TAPERING SIDES OF SAID RIB BRICK AND BEING SUPPORTED BY SAIDRIB BRICK AND THUS PLACING SAID PARTITIONED SECTIONS IN SERIES LATERALLYWITH RIB BRICK IN THE ADJACENT RIBS.